Rotary spiral sieve.



J. S. FASTING.-

ROTARY SPIRAL SIEVE: APPLICATION FILED JANL18,1910.-

Patented July 4, 1911.

2 SHEETS-SHEET 1.

COLUMBIA PLANOGRAPH 60., WASHINGTON. D. c.

J. s. FASTING. ROTARY SPIRAL SIEVE. APPLICATION FILED JAN. 18,1910.

997,185, 1 Patented Ju1y4, 1911.

2 SHEETS-SHEET 2.

COLUMBIA PLANOORAPH co.. WASHINGTON, b. c.

UNITED STATES PATENT OFFICE.

JOI-IAN SIGISMUND FASTING, OF FREDERIKSBERG, NEAR COPENHAGEN, DENMARK,ASSIGNOR TO F. I. SMIDTH &; (30., OF NEW YORK, N. Y., A CORPORATION OFNEW JERSEY.

ROTARY SPIRAL srnvn.

Specification of Letters Patent.

Patented July 4, 1911.

To all whom it may concern:

Be it known that I, JOHAN SIGISMUND FASTING, a subject of the King ofDenmark, residing at Frederiksberg, near Copenhagen, Denmark, haveinvented certain new and useful Improvements in Rotary Spiral Sieves, ofwhich the following is a specification, reference being had to theaccompanying drawings, forming a part hereof.

This invent-ion relates to rotary sleves for the separation of the finerand coarser particles of pulverized cement and othermaterials. Inaccordance with the invention asifting drum, having spirally disposedwalls which are perforated in part to permit the passage therethrough ofthe finer material, is arranged to rotate upon a substantiallyhorizontal axis. The material to be sifted is fed to the drum at one endand the coarser particles are allowed to escape at the other end. Meansare provided for directing a current of air into the central portion ofthe drum and the air is allowed to escape through the spiral passageformed by the spirally disposed walls and through an opening in theperiphery of the drum. The outer portions of the spiral wall or Wallsare imperforate and the drum is rotated in the direction of the spiralwinding of the walls. The coarser particles of the material to be siftedare therefore continually re turned toward the axis of rotation of thedrum and as the finer particles fall through the perforations of theinner portions of the spiral walls they are caught up by the current ofair which is directed against them at right angles to their direction offall and are carried with the current of air outward through the spiralpassages of the drum to the peripheral opening from which they aredischarged separately from the coarser particles. As the current of airloses its velocity as it passes from the peripheral opening, the finerparticles, theretofore borne by the current of air, are precipitated andfall into the receptacle provided therefor. Should it be found that theair carries with it in suspension some of the finest particles of thematerial, the air may be returned to its source of supply and so passedthrough the apparatus continuously, the same air being used over andover again.

The invention will be more fully explained hereinafter with reference tothe several embodiments thereof shown in the accompanying drawings, inwhich Figure 1 is a view in axial section of one" form of the apparatus.Fig. 2 is a View in transverse section of the apparatus shown in Fig. 1.Fig. 3 is a view similar to Fig. 1 but showing a different form of theapparatus. Fig. 4: is a view in transverse section of the apparatusshown in Fig. 3.

In the apparatus shown in Figs. 1 and 2 a fixed casing 1 is providedwith an inlet 2 through which the air is supplied under pressure and, itmay be, with a separate inlet 14 for the material to be sifted, thelatter being provided, if necessary, with a check valve 13 to preventthe air admitted under pressure through the inlet 2 from passing outthrough the inlet 14. Mounted in suitable bearings which may besupported on the casing 1 is a substantially horizontal shaft l whichsupports the spiral drum 5. The end .wall 6 of the drum is provided witha central opening for the admission of the material to be sifted and ofthe air to the central portion of the drum, while the end wall 7 isprovided with a spiral, annular opening, the outer margin of which maybe defined, in part at least, by the perforated, inner portion of thespiral wall 5. The coarser particles of the material to be sifted passlongitudinally along the perforated wall from the inlet end to theoutlet end from which they may pass through a discharge passage 9 intothe casing 11 of a spiral conveyer 10.

The finer particles of the material to be sifted, as they fall throughthe perforations of the inner portion of the spiral wall 5 are caught upbythe current of air which is directed from the central portion of thedrum into the spiral passage formed by the spiral wall, such current ofair striking the particles substantially at a right angle to theirdirection of fall, as clearly indicated in Fig. 2. As the air passes onthrough the spiral passage it carries with it, in suspension, the finerparticles out through the peripheral opening in the wall of the spiral,rotating drum. As the air passes out through this opening it loses itsvelocity and the finer particles theretofore carried in suspension areprecipitated and fall to the conveyer at the bottom thereof. The bladeor web of the latter is formed in two parts, spirally wound in oppositedirections so that when the conveyer is rotated in the proper directionthe coarser particles will be delivered at one end thereof and the finerparticles at the other end. The conveyer may be driven by any suitablemeans, such as a belt 12 passing over a pulley 011 the shaft of theconveyer and a pulley on the shaft 4 of the spiral drum. Such of thecoarser particles as are not carried forward at first by the current ofair, but are fine enough to pass through the perforations of the drumare returned by the outer, imperforate portions of the spiral wall tothe central portion of the drum where they may fall again throughthe'perforations, thus having another opportunity to be taken up andcarried forward by the current of air. Such particles as are not thuscaught up by the current of'air eventually pass out with the coarsestparticles through the discharge passage 9. Obviously, the perforationsin the inner portion of the spiral wall may be arranged in groups or inany suitable manner to permit the desired results to be obtained.Obviously, also the air might be conducted from the outlet 3 of thecasing 1 to the pump or fan by which the air is delivered to the inlet 2so that it may be used over and over again should it be found that thefinest particles of the material are carried in suspension with the airthrough the air outlet 3.

In the embodiment of the invention illus trated in Figs. 3 and 4 thespiral, rotating drum, supported as before upon the shaft t and providedwith a combined air and material inlet 14, is formed of a spiral wall 5,the inner portion of which is perforated, and a spiral imperforate plate21. The fan casing 15 is in'this case secured to the spiral drum so thatit rotates therewith, the air being discharged by the fan 16 into thespiral drum through an opening which extends along the entire length.The fan 16 may be driven by pulleys 17 and 18 on the shaft 4 of the drumand on the shaft of the fan 16 respectively and a belt 19. The materialto be sifted is delivered into the spiral passage between the spiralwall 5 and the spiral plate 21 and, by the rotation of the drum in theproper direction, is carried back into the central portion ofthe drumwithin the perforated portion of the wall 5 so that the finer particleswhich pass through the perforations may be caught up by the current ofair which is directed into the drum in the same manner and eventuallypass through the passage to the peripheral opening, carrying with it thefiner particles in suspension, such finer particles being precipitatedas the current of air loses its velocity after passing through theperipheral opening. The coarser particles eventually pass out throughthe opening at the outlet end of the drum and are deposited separatelyfrom the finer particles.

Various other changes in details of construction and arrangement may bemade to suit different considerations of use without departing from thespirit of the invention.

I claim as my invention:

1. A rotary sieve comprising a rotary drum having a spiral perforatedwall and having in its periphery an opening for the discharge of thefiner material and. in its end an opening for the discharge of thecoarser material, means to rotate the drum in the direction of thespiral winding of its wall, and means to direct a current of air in thesame direction through the spiral passage formed by the spiral wall andthrough the peripheral opening.

2. A rotary sieve comprising a rotary drum having a spiral wall with itsinner portion perforated and its outer portion imperforate and having inits periphery an opening for the discharge of the finer material and inits end an opening for the discharge of the coarser material, means to1'0- tate the drum in the direction of the spiral winding of its wall,and means to direct a current of air in the same direction through thespiral passage formed by the spiral wall and through the peripheralopening.

1 3. A. rotary sieve comprising a rotary drum having a spiral perforatedwall and having in its periphery an opening for the discharge of thefiner material and in its end an opening for the discharge of thecoarser'material, means to rotate the drum in the direction of thespiral winding of its wall, means to direct a current of air in the samedirection through the spiral passage formed by the spiral wall andthrough the peripheral opening, and a casing surrounding the drum andhaving an opening for the discharge of air and an opening for thedischarge of the finer material precipitated within the casing.

4:. A rotary sieve comprising a rotary drum having a spiral perforatedwall and having in its periphery an opening for the discharge of thefiner material and in its end an opening for the discharge of thecoarser material, means to rotate thedrum in the direction of the spiralwinding of its wall, means to direct a current of air in the samedirection through the spiral passage formed by the spiral wall andthrough the peripheral opening, and a casing surrounding the drum andhaving an opening in its bottom for the discharge of the finer materialand forming at its end a passage for the discharge of the coarsermaterial.

5. A rotary sieve comprising a rotary drum having a spiral perforatedwall and having in its periphery an opening for the discharge of thefiner material and in its end an opening for the discharge of thecoarser material, means to rotate the drum in the direction of thespiral Winding of its Wall, means to direct a current of air in the samedirection through the spiral passage formed bv the spiral Wall andthrough the peripheral opening, a casing surrounding the drum and havingan opening in its bottom for the discharge of the finer material andforming at its end a passage for the discharge of the coarser material,and a spiral conveyer in the bottom of the casing having its blade orWeb Wound spirally in opposite directions to discharge at one end thefiner material from the bottom of the casing and at its other end thecoarser material from said passage.

In Witness whereof, I have hereunto signed my name in the presence oftWo subscribing Witnesses.

J OI-IAN SIGISMUND FASTING.

Witnesses:

HERMAN REE, JULIUS LEHMANN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, I). C.

